Protective apparatus



May 29, 1928. 1,671,492

M. E. SKINNER PROTECTIVE APPARATUS Fiied Feb. 8, 1923 WITNESSES: 7 INVENT( )R Merv/ll E. Skmner W BY WW Patented May 29, 1928.

UNITED STATES PATENT OFFICE.

MERRILL IE. SKINNEB, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

PROTECTIVE AQPPARATUS.

Application filed February 8, i923, Serial 1T0. 817,887;

connection with which explosive mixtures or other undesirable mixtures may be formed.

My invention has for one of its objects to provide a simple arrangement whereby inert gas may be supplied to a container at a substantially constant pressure.

A second object of my invention is to provide means whereby inert gas may be supplied at any desired lower pressure from a tank under relatively high pressure.

Another object of my invention is to provide means for insuring that the pressure within a container does not fall below a predetermined value or exceed a second and higher predetermined value.

-A further object of my invention is to provide means whereby inert gas is supplied to a container when the pressure t erein falls to a predetermined valueabove atmospheric pressure and gas is permitted to es-, 2 cape therefrom when the pressure therein exceeds a second and higher predetermined value.

In the operation of electrical apparatus such, for example, as transformers, circuit 3 breakers and the like, in which insulating oil is employed to surround the electrical devices, it has been found that the oil .deteriorates rapidly when it is in contact'with air, causing the formation of sludge, the absorption of ,moisture, and the loss, to a cer;

tam degree, of the insulating properties of faults in the electrical apparatus occur, below the surface of the oil, the molecular composition of the oil is broken down and explosive mixtures may be formed when the liberated gases unite with the air in the space above the oil. I

In accordance with the present invention,

I provide means whereby a blanket of inert gas is maintained at a substantially constant pressure in the space above the oil in a casing or container for electrical or other apparatus. Y Inthe preferred form of my invention,

a tank of inert gas such, for example, as

nitrogen, carbon dioxide, or other suitable gas, under relativelyhigh pressure, is conneoted to. the space above the insulating oil. The transfer of gas from the tank to the casing or container is controlled by means of a reducing valve and a pressure-regulating valve of well-known type. A relief valve operates to relieve the pressure within the tank when it exceeds a desired predetermined maximum value.

The single figure of the accompanying drawing is a view, partially in section and partially in elevation, of an oil-containing casing with my invention applied thereto.

A container or casing 1, which may be, for example, that of a transformer, circuit breaker or other apparatus (not shown) is filled with oil, indicated at 2', to any deslred level. A cover member 3 is fitted to the body of the container 1 in any suitable gas tight manner to enclose a space 4 above the level of the oil. A tank 5, which may be filled with inert gas, such, for example, as

nitrogen, carbon dioxide, or other suitable gas, under high pressure, is connected to the space 4 through a reducing valve 6, and a differential valve 7, which operates in a wellknown manner in accordance with the pressure within the space 4.

The space 4 is provided with a reller valve 8, which may be of any suitable character, but which is illustrated, by way of GX? ample, as having the form of a. U-tube 9 that is filled with mercury, indicated at 10, to any desired level in accordance with the pressure at which it is desired to,operate.

In practice, I prefer to employ the valve 'the Westinghouse Electric .& Manufacturing the oil. It has been found also that, when G ompany.

operatively connected, as shown and described. It may be assumed further that the valves 6 and 7 have been temporarily adjusted to such values as to supply inert gas under pressure to force the air out of the space 4. throughthe relief valve 8 or through any suitable opening that may be provided in the container 1 or the cover member 3- It may be assumed, also, that the pressure within Itlhe gas tank 5 is 250 pounds per square 111C The reducing valve-6 and the pressureregulating valve '7 are adjusted to supply inert as to the space 4 at a pressure that is slig tly above atmospheric pressure, for example, two pounds per square inch. The relief valve 8 may be arranged to operate,

It may be assumed that the apparatus is.

for example, at a ressure within the container of five poun s per square inch above atmospheric pressure.

In case the apparatus within the container 1 is of such nature that its temperature varies, the volume of oil 2 varies correspondjusted. The quantity of gas remaining within the space 4 remains constant while its volume diminishes until the pressure reaches the value of five pounds, for which the relief valve 8 is adjusted. The gas is then permitted to escape through the column of mercury 10 in the latter.

When the temperature within the container 1 falls and the volume of the oil 2 diminishes correspondingly, the pressure within the space 4 falls at a corresponding rate and, when it reaches the value of two pounds per square inch above atmospheric pressure, inert .gas is then supplied from the tank 5, whereby the ,pressure' in the tank does not fall to a value approximately equal to atmospheric pressure. Accordingly, there is no possibility of air entering or leaking into the transformer through an small openings that may develop during its oper= ation.

It will be understood that no gas is supplied to the container 1 or escapes therefrom so long as the pressure within the space 4 V is within the limits for which the pressureregulating valve 7 and the relief valve 8 are adjusted. It is obvious, also, that the pressure at which gas is supplied to the space 4 maybe regulated, as desired, by varyin the adjustment of the reducing valve 6 an the regulating valve 7. The maximum pressure that may exist within the space 4 may be. adjusted by suitably varying the quantity of mercury within the valve 8. v

If desired, a relief valve of the springcontrolled type, may be substituted for the U-tube, which is shown by Way of example only in order that the principle of operation ma be clearly understood.

ny suitable means, such, for example, as a pressure gauge (not shown) may be emgloyed in connection with the space 4 to inicate a pressure therein that is below the normal. operating pressure to inform the operator that the supply or gas in the tahk 5 is approaching depletion.

The advantages in employing protective apparatus of the character described above are that the oil is never in contact with air,

and all oxidation of the oil and its deteriorationby reason. of sludging is avoided. In case faultsdevelop in the electrical apparaterrace are not dangerous because no explosive mixture is formed. in the space 4. This arrangement efiectually prevents also the entrance of air which contains moisture that may be absorbed by the oil. It has been found also that any air and moisture originally in the oil are gradually removed therefrom by drf fusion and that the oil absorbs a certain amount of inert. gas which increases its 1nsulating properties.

While my invention is particularly adapted for use in connection with electrical apparatus, it will be understood that its application is not limited other than is specified in the accompanying claims.

I claim as my invention 1. The combination with a container havtherein is within predetermined limits, and

means for varying the range between said limits.

3. The combination with a container havinga quantity of oil therein and a'space above said oil, of a tank of inert gas under relatively high pressure connected to said space, a reducing valve and a pressure-regulating valve between said tank and said container whereby inert gas is supplied to the latter at a relatively low pressure and means for relieving the pressure within said container when it exceeds a predetermined value. 7

4. The combination with a casing, of an insulating liquid medium partially filling said casing, anelectrical translating device immersed in said liquid medium, means for passing inert gas into the region above said sive to the pressure, of the gas in said region for controlling the rate of flow thereof. 3 5. The combination with a casing, of an insulating liquid medium partially filling said casing, an electrical translating device immersed in said liquid medium, means for passing inert gas into the region above said liquid medium, and means comprising a differentially controlled valve directly responsive to the pressure of the gas in said region for controlling the rate of flow thereof.

6. The combination with a casing, of an insulating liquid medium partially filling said casing, an electrical translating device .liquid medium, and means directly responimmersed in said liquid medium, means for passing inert gas into the region above said liquid medium, means directly responsive to the pressure of the gas in said region for controlling the rate of flow thereof, and

means responsive to the pressure of the gas in said region for controlling the passage thereof from said casing upon occurence of excessive pressure.

In testimony whereof, I have hereunto I subscribed my name this fifth day of February 1923.

MERRILL E. SKINNER. 

